The present invention relates in general to power plants and their emissions, and in particular to a new and useful system and method for increasing the efficiency of power plants using condensing heat exchangers.
It is well-known in the power plant field to use a dry scrubber for controlling emissions of sulfur dioxide (SO.sub.2) contained within the flue gas produced by these plants. It is a common problem or process constraint for power plants employing dry scrubbers to maintain a minimum gas temperature for the dry scrubber which is required for a flue gas scrubbing process. This minimum gas temperature is established by the requirements for evaporating water in a scrubber slurry in the dry scrubber while still achieving the desired temperature in the scrubber process.
As a general rule, the greater the sulfur content of the flue gas and the greater the required SO.sub.2 removal efficiency, the higher the minimum gas temperature is required for the dry scrubber. This minimum gas temperature requirement sets a limit on the achievable efficiency for the boiler, i.e. the ability to minimize the heat loss in the exhaust gas, and thus limits the efficiency of the cycle.
U.S. Pat. No. 4,956,162 to Smith et al. discloses a known system for removing SO.sub.2 from a flue gas. This system, however, has a limited cycle efficiency due to the minimum gas temperature requirements as described above.
Presently, there is no known system or method which can improve the cycle efficiency for a dry scrubber system.